Novel ruthenium(III) complexes with histamine [RuCl(4)(dmso-S)(histamineH)] . H( (2) )O (1a) and [RuCl(4)(dmso-S)(histamineH)] (1b) have been prepared and characterized by X-ray structure analysis. Their crystal structures are similar and show a protonated amino group on the side chain of the ligand which is not very common for a simple heterocyclic derivative such as histamine. Biological assays to test the cytotoxicity of the compound 1b combined with electroporation were performed to determine its potential for future medical applications in cancer treatment.